Such a headrest is described in DE 199 51 966. In the headrest, a cushion body with at least two pivoted levers that are spaced from each other can be displaced between a rear starting position and a working position and can be locked in the working position. The locking is done by a pivoted part that is fixed to a base at a post. The pivoted part is equipped with an extension which is in contact with the cushion body, and prevents a backward motion of the cushion body. The pivoted part can be locked in various positions with a catch mechanism, whereby the positions of the pivoted part are associated with different positions of the head contact part.
DE 102 02 598 describes a headrest that comprises a base, as well as a parallel element that is pivotally mounted on the base. The parallel element can be displaced relative to the base and can be fixed in the selected position by blocking means. In accordance with the invention, the blocking means are formed by a coil spring, by means of which the parallel element can be retained in the selected position by a frictional connection.
U.S. Pat. No. 7,520,564 describes a headrest that has a base retained by being fixed to a post, as well as a head contact part is mounted on the base via a lever system. The head contact part comprises an elongated hole in which a pin is guided that is associated with a lower lever of the lever system. In this way, different sequences of motions are possible between the parallel element and the base.
DE 203 21 462 describes a headrest where a head contact part is mounted on a base, displaceable with upper and lower links. In the case of a crash, the head contact part can be moved forward from a rear starting position into a crash position that is blocked toward the rear by a crash blocker. Beyond that, a catch mechanism permits the adjustment of the head contact part at various comfort settings. In the respectively selected position, the head contact part can be moved into a different position by overcoming the retention force of a catch spring.